RBY Basic Teambuilding

Unless you are very very experienced at Gen 1 OU, I recommend structuring a team like this:
Lead
Big 4
Wildcard

Lead options: Jynx/Alakazam/Gengar/Starmie [Exeggutor can be used as a lead too, but that complicates things, so for the sake of simplicity, ignore it]
Big 4: These are Snorlax, Chansey, Exeggutor, Tauros
Wildcard: Common options include Slowbro, Golem, Rhydon, Lapras, Alakazam, Starmie, Cloyster, Zapdos

Smogon's Analysis sets are generally suitable (one or two might be a bit outdated), but here's a sample set for each listed pokemon. [There's no Items or EVs, so only moves need to be listed]. Some Pokemon can run other sets viably, but these are the pokemon's main sets.

Leads
Jynx - Blizzard/Psychic/Lovely Kiss/Rest [Last option is filler, moves such as Mimic, Body Slam, and Counter can all work too]
Gengar - Hypnosis/Explosion/Night Shade/Thunderbolt
Alakazam - Psychic/Seismic Toss/Thunder Wave/Recover [When run outside of the lead spot, try Psychic/Reflect/Thunder Wave/Recover instead]
Starmie - Psychic/Blizzard/Recover/Thunder Wave [Use Thunderbolt over Psychic if you want if not running it as a lead]

Big 4
Snorlax - Body Slam/Earthquake/Hyper Beam/Self Destruct
Chansey - Thunder Wave/Thunderbolt/Ice Beam/Softboiled
Tauros - Body Slam/Earthquake/Blizzard/Hyper Beam
Exeggutor - Sleep Powder/Psychic/Explosion/Stun Spore [Mega Drain and Hyper Beam are also options in the last slot]

Wildcard
Slowbro - Amnesia/Thunder Wave/Rest/Psychic [Surf is also an option]
Golem - Rock Slide/Earthquake/Explosion/Body Slam
Rhydon - Rock Slide/Earthquake/Body Slam/Substitute
Lapras - Blizzard/Thunderbolt/Sing/Hyper Beam [Also try Confuse Ray and Body Slam]
Cloyster - Clamp/Blizzard/Explosion/Hyper Beam
Zapdos - Thunderbolt/Drill Peck/Thunder Wave/Agility [Lots of possibilities in the last slot. Also try Reflect, Light Screen, Hyper Beam]

Was made originally for use by the Pokemon Showdown Tournaments room.